Interdigitated Flow Fields for Thin Electrode Power Density
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Solution Overview
Problem
Conventional flow batteries face inefficiencies in energy storage and discharge due to thick electrodes required for full electrolyte flow, leading to high ohmic losses and lower power density.
Innovation Solution
The implementation of interdigitated flow fields with partially blocked outlets and inlets in flow batteries forces electrolyte flow under ribs, allowing for thinner electrodes and enhanced reactant transport, reducing pressure drop and ohmic losses while increasing power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If thick electrodes are used to allow full electrolyte flow, then electrolyte transport is improved, but ohmic losses increase and power density decreases
Solution Approach 1:
The electrode is segmented into flow channels and flow chambers by ribs. The flow channels provide dedicated pathways for electrolyte transport, while the flow chambers facilitate electrochemical reactions. This segmentation allows thin electrodes to achieve effective electrolyte transport without requiring thick electrode structures, thereby reducing ohmic losses while maintaining adequate reactant supply.
Solution Approach 2:
The patent introduces a third dimension by creating flow chambers between the electrode surface and the flow field plate. This vertical dimension (depth) allows electrolyte to access the electrode surface from multiple directions, enhancing transport efficiency without increasing the lateral thickness of the electrode, thus reducing ohmic resistance.
2Quantity of substance
If thick electrodes are used to allow full electrolyte flow, then electrolyte transport is improved, but power density decreases
Solution Approach 1:
By segmenting the electrode structure into flow channels and flow chambers separated by ribs, the patent creates efficient pathways for electrolyte transport that do not require thick electrodes. This maintains high surface area for electrochemical reactions, thereby preserving high power density while ensuring adequate electrolyte supply.
Solution Approach 2:
The flow field plates are designed with porous structures that facilitate electrolyte distribution and access to the electrode surface. This porous architecture enhances mass transport efficiency without requiring thick solid electrodes, maintaining high power density through improved reactant availability at the reaction sites.
3Loss of energy
If thin electrodes are used, then ohmic losses are reduced and power density increases, but electrolyte transport becomes insufficient
Solution Approach 1:
The segmented structure with dedicated flow channels provides efficient electrolyte transport pathways that compensate for the reduced electrode thickness. The ribs create a network of channels that ensure adequate electrolyte supply to all active areas of the thin electrode, maintaining sufficient mass transport without requiring thick electrode structures.
Solution Approach 2:
By utilizing the vertical dimension to create flow chambers between the electrode and flow field plate, the patent enables enhanced electrolyte access from multiple directions. This three-dimensional flow architecture ensures sufficient electrolyte transport to thin electrodes by providing multiple access paths, compensating for the reduced lateral thickness.
4Device complexity
If conventional flow fields are used, then electrode structure is simple, but pressure drop is high and performance is limited
Solution Approach 1:
The segmented flow field design with ribs creating multiple flow channels distributes electrolyte flow more evenly across the electrode surface. This segmentation reduces flow resistance and pressure drop compared to conventional single-channel designs, while the modular rib structure maintains relative simplicity in manufacturing and assembly.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables thinner electrodes with reduced ohmic losses and higher power density, exceeding conventional flow battery performance by achieving power densities greater than 0.3 W/cm2 compared to the typical 0.1 W/cm2.
Implementation Method 1
The ion-exchange membrane prevents the electrolytes from mixing but permits selected ions to pass through to complete the redox reactions
Implementation Method 2
restricting flow of a liquid electrolyte through the first channels using the at least partially blocked outlets of the first channels to force flow of the liquid electrolyte through the adjacent respective first liquid-porous electrode or second liquid-porous electrode
Implementation Method 3
A negative electrolyte is delivered to the negative electrode and a positive electrolyte is delivered to the positive electrode to drive an electrochemically reversible redox reaction
Data Source
AI summary
A flow battery includes a first liquid-porous electrode, a second liquid-porous electrode spaced apart from the first liquid-porous electrode, and an ion-exchange membrane arranged between the first liquid-porous electrode and the second liquid-porous electrode. First and second flow fields are adjacent to the respective first liquid-porous electrode and second liquid-porous electrode. Each of the flow fields includes first channels having at least partially blocked outlets and second channels having at least partially blocked inlets. The second channels are interdigitated with the first channels. The flow fields provide a configuration and method of operation for relatively thin electrodes with moderate pressure drops and forced convective flow through the liquid-porous electrodes.